of the Russian ruler and Ukraine was taken under the protection of the Tsardom of Russia. Ukrainians of all ranks gathered, or were compelled to gather in Kiev and other towns to take oath of fealty; part of the secular and Orthodox clergy leaders objected or refused. The actual agreement was finalized in April in Moscow, where the Cossack emissaries managed to convince the Tsardom to accept a majority of the Cossack demands (the degree of Ukrainian autonomy was specified) and obtain the promise of Russian intervention in the Commonwealth. The Cossack hetman and his advisers meant a military alliance to facilitate common fight against Poland, even at the price of losing some of the sovereignty acquired in recent years; to Russia a new avenue for imperial expansion was opened. The Treaty of Pereyaslav, an act of "unification of Ukraine with Russia", was from the Commonwealth's point of view an instance of rebellion combined with foreign meddling. It led to a new Russo-Polish war that lasted from 1654 to 1667. Powerful Russian armies entered the Commonwealth and the conflict with the Cossacks became a war with the Tsardom. The Russian plans included not only incorporation of Ukraine, but also recovery of the lands lost by Russia further north. The Ottoman Empire and the Crimean Khanate, worried by the new configuration, were now inclined to support the Commonwealth. With the Tatars the Polish units waged a destructive raid into Ukraine and fought in early 1655 the victorious Battle of Okhmativ against combined Russian and Ukrainian forces. Later that year Khmelnytsky counterattacked, took Lublin and reached the Vistula, but was forced to acknowledge John Casimir's supremacy again when his efforts were thwarted by the Tatars. Until his death in 1657 the Cossack leader, despite the Pereyaslav treaty, conducted independent policy, intent on taking advantage of the calamities that had befallen upon the Commonwealth, but also considered an improvement of the relationship with the great power that he shook up ("fatally wounded", according to historian Timothy Snyder). In the Grand Duchy of Lithuania the first phase of the war with the Tsardom ended with a total defeat of the Commonwealth. At the Battle of Shklow (1654) and the Battle of Shepelevichy the Russians destroyed the small Lithuanian force under Janusz Radziwiłł. The country laid open to the conquerors. Belarusian towns surrendered one after another and in 1654 Smolensk fell after a three-month-long siege.